Computing distance, part one 
Given an undirected graph G=(V,E), we previously defined the distance between two nodes x and y as the length of a shortest path in G from x to y. Now we describe how to compute this value. Computing distance in a graph relates to several important topics in Web science:
Computing distance in a graph is also very closely related to computing shortest paths in a graph. Finding shortest paths is a fundamental problem in computer science that is traditionally solved with breadthfirst search. Our distance algorithm is a slightly simplified version of breadthfirst search. We motivate our distance algorithm with the following scenario:
Given the above scenario, who will receive meme m from whom, and how many steps will it take for m to reach each person in the network? Answering these questions drives the distance algorithm. Example:
